Fuel Gauge Not Working

Message Topic Search Topic Options Post Reply Create New Topic Printable Version Translate Topic

   I am having trouble with the fuel gauge on my 1964 Rambler Classic 660. I have searched the forum and see that this has been a regular question to pop up. I have read as many of the conversations as possible so I would not pester you guys with the "same old issue". I believe the gauge might need replacing and would like to get some second opinions before I go that route.
The following tests mentioned in posts on the forum have been performed:

1. Took car for a errand run/road test to verify the temp gauge moves. It does a little, but nowhere near as much as it should considering it was a 32 mile round trip.

2. Grounded temp sending unit to clarify the temp gauge would move higher than than it did during the road test. Gauge shot up as expected. So the temp gauge checks out.

3. Verified that there is a good ground from the fuel tank to the car body.

4. Grounded wire from fuel sending unit to car body and the gauge did not move.

5. Checked continuity of the wire from tank to gauge and it came out clear.

6. Dropped tank and removed fuel sending unit and checked the Ohms. Readings check out as being between 78 and 10 Ohms. So the sending unit appears fine.

7. With the instrument cluster removed and 12 volts supplied to the cluster, I measured roughly 5 pulsating volts from both terminals on the back of the fuel gauge. (For the sake of curiosity, I checked the terminals on the temp gauge as well with the same results.) This would seem to mean the instrument cluster voltage regulator is working correctly. 

So, I have come to the conclusion that the fuel gauge needs to be replaced. Any opinions? I really do not know much about electronics in vehicles, so my above conclusions could be completely off the mark. 

If I should replace the gauge, are there any tips for undoing the crimps on the cluster without marring or damaging the clear front of the cluster?

Thanks guys for any help!!!

Author	Message Topic Search Topic Options Post Reply Create New Topic Printable Version Translate Topic
Metacomet64 Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Fan Joined: Jan/24/2019 Location: Foley, Alabama Status: Offline Points: 3	Post Options Post Reply Quote Metacomet64 Report Post Thanks(0) Quote Reply Topic: Fuel Gauge Not Working Posted: Feb/03/2019 at 6:16pm
	I am having trouble with the fuel gauge on my 1964 Rambler Classic 660. I have searched the forum and see that this has been a regular question to pop up. I have read as many of the conversations as possible so I would not pester you guys with the "same old issue". I believe the gauge might need replacing and would like to get some second opinions before I go that route. The following tests mentioned in posts on the forum have been performed: 1. Took car for a errand run/road test to verify the temp gauge moves. It does a little, but nowhere near as much as it should considering it was a 32 mile round trip. 2. Grounded temp sending unit to clarify the temp gauge would move higher than than it did during the road test. Gauge shot up as expected. So the temp gauge checks out. 3. Verified that there is a good ground from the fuel tank to the car body. 4. Grounded wire from fuel sending unit to car body and the gauge did not move. 5. Checked continuity of the wire from tank to gauge and it came out clear. 6. Dropped tank and removed fuel sending unit and checked the Ohms. Readings check out as being between 78 and 10 Ohms. So the sending unit appears fine. 7. With the instrument cluster removed and 12 volts supplied to the cluster, I measured roughly 5 pulsating volts from both terminals on the back of the fuel gauge. (For the sake of curiosity, I checked the terminals on the temp gauge as well with the same results.) This would seem to mean the instrument cluster voltage regulator is working correctly. So, I have come to the conclusion that the fuel gauge needs to be replaced. Any opinions? I really do not know much about electronics in vehicles, so my above conclusions could be completely off the mark. If I should replace the gauge, are there any tips for undoing the crimps on the cluster without marring or damaging the clear front of the cluster? Thanks guys for any help!!!

mmaher94087 Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Apr/01/2008 Location: Arizona Status: Offline Points: 1690	Post Options Post Reply Quote mmaher94087 Report Post Thanks(0) Quote Reply Posted: Feb/03/2019 at 6:37pm
	Check the nuts on the back of the gauge and check that you have a good ground between the cluster and the car body.
	Mike

Metacomet64 Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Fan Joined: Jan/24/2019 Location: Foley, Alabama Status: Offline Points: 3	Post Options Post Reply Quote Metacomet64 Report Post Thanks(0) Quote Reply Posted: Feb/04/2019 at 10:15am
	Thanks for the tip. I will give that a try!

farna Members Profile Send Private Message Find Members Posts Add to Buddy List Supporter of TheAMCForum Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19676	Post Options Post Reply Quote farna Report Post Thanks(0) Quote Reply Posted: Feb/12/2019 at 6:42am
	Any time both the fuel and temp gauge have the same faulty signs (both reading high or low, or not at all) the regulator is most likely bad. Best replacement is a LM7805 electronic regulator. You can probably find an original type, but the electronic one is easy and reliable, and unseen. http://worldpowersystems.com/AMC/dashreg/index.html That said, you stated that the temp gauge worked as expected when grounded, so the regulator is probably fine. Since the fuel sending unit checks out but grounding the wire didn't peg the gauge at full, you either have a gauge or wire problem. Check the connections as suggested. If that doesn't do the trick, attach a grounded wire to the fuel gauge post and see if the gauge pegs. If it does the wire between gauge and sending unit is broken somewhere. If not, the gauge itself is bad.
	Frank Swygert